1. Field of the Invention
The present invention relates to a rocker pin for use in rocker joints for connecting link plates of a power transmission chain and also to a wire stock for producing the rocker pin.
2. Description of the Related Art
In general, a conventional rocker joint used for connecting link plates of a power transmission chain is formed by a pair of rocker pins 1, 2 of different lengths arranged face to face in a manner as shown in FIG. 9. FIG. 10 is an end elevation of FIG. 9, which shows the longer pin 1 and the shorter pin 2 are identical in cross section and have the same thickness T.
In one silent chain proposed by the present assignee, link plates are connected together by rocker pins with non-uniform pitches. To provide such non-uniform link plate pitches, rocker pins having different thicknesses are used in combination. This arrangement requires producing and storing at least two kinds of rocker pins of different thicknesses and a like number of wire stocks of different thickness used for the production of the rocker pins.
In another silent chain, more than two kinds of rocker pins having rocker surfaces of different profiles are used in combination. In this case, it is likewise required to produce and store more than two kinds of rocker pins with different rocker surface profiles and a like number of wire stocks with different prospective rocker surface profiles for producing the rocker pins. However, each of the conventional rocker pins or the wire stocks does not have any means for distinguishing itself from another rocker pin or wire stock having a different thickness or a different rocker surface profile.
Consequently, the conventional rocker pins and wire stocks used for producing the same have the following problems:
(1) Due to the similarity in shape and configuration, the conventional rocker pins or wire stocks are not easy to distinguish from one another, requiring great care to avoid confusion when they are to be handled for storage, transportation and assembly.
(2) If two or more kinds of rocker pins of different thicknesses or different rocker surface profiles are inadvertently mixed together, sorting of the mixed rocker pins would be practically impossible because it would require measurement of individual rocker pins. For mass-produced chains, tens of thousands of rocker pins are handled as a single batch. It is, therefore, substantially impossible to measure the rocker pins one by one to sort out them. The mixed rocker pins are finally disposed as waste.
(3) If the longer pin and the shorter pin are incorrectly combined in any of the rocker joints of a silent chain, the silent chain is unable to achieve its prescribed function because an appropriate clearance is not provided between a pin-accommodating hole in the link plate and the rocker pins. Further, if the outside diameter of the rocker pins used in combination is larger than the diameter of the pin-accommodating hole of the link plate, the rocker pins cannot be inserted into the pin-accommodating hole, causing a damage to the machine used for assembling the silent chain.
It is an object of the present invention to provide a rocker pin which can be easily and visually distinguished by human eyes from another rocker pin having a different thickness or a different rocker surface.
It is another object of the present invention to provide a wire stock for producing rocker pins, which stock can be easily distinguished by human eyes from another wire stock used for producing rocker pins of a different thickness or a different rocker surface.
According to a first aspect of the present invention, there is provided a rocker pin having a given thickness and a peripheral surface including a convexly arcuate rocker surface, and further having an identifying means for distinguishing the rocker pin from another rocker pin having a different thickness or a different rocker surface.
In one preferred embodiment, the identifying means is provided on the peripheral surface except the rocker surface. The identifying means may include at least one groove, ridge, colored mark or streak having a different luster from that of the other surface, extending in the longitudinal direction of the rocker pin. The identifying means preferably extends from end to end along the full length of the rocker pin.
In another preferred embodiment, the identifying means is provided on at least one end face of the rocker pin. The end face preferably comprises an arcuate surface, an angled or V-shaped surface, or a like surface other than a surface extending perpendicularly to the longitudinal axis of the rocker pin. It is preferable that when identifying means is provided on both end faces of the rocker pin, the shape of one end face is complementary in contour to the shape of the other end face.
In yet another preferred embodiment, the peripheral surface further includes a back surface opposite to the rocker surface and a pair of side surfaces connecting the rocker surface and the back surface, and the identifying means comprises a beveled surface formed at an edge that is formed by the rocker surface and one of the side surfaces.
According to a second aspect of the present invention, there is provided a continuous wire stock to be severed into rocker pins of a predetermined length, which wire stock has a given thickness and a peripheral surface including a convexly arcuate prospective rocker surface, and further has an identifying means for distinguishing the wire stock from another wire blank having a different thickness or a different prospective rocker surface.
The identifying means preferably comprises least one groove, ridge, colored mark or streak having a different luster from that of the other surface. The identifying means is provided on the peripheral surface other than the prospective rocker surface and a part of extends in the longitudinal direction of the wire stock. The identifying means preferably extends along the full length of the wire stock. Instead, the identifying means can be formed by and end surface other than a surface perpendicular to the axis in the longitudinal axis of the wire stock, for example, a curved surface or a sloped surface.
By thus provided identifying means, it is easy to identify visually at least two kinds of rocker pins or wire stocks having different thicknesses or different rocker surfaces. Further, this fact makes it possible to prevent the mixture of different kinds of rocker pins or wire stocks and to prevent incorrect combination of a longer pin and a shorter pin constituting a rocker joint.
The above and other objects, features and advantages of the present invention will becomes apparent to these versed in the art upon making reference to the following detailed description and accompanying sheets of drawings in which certain preferred structural embodiments incorporating the principle of the present invention are shown by way of illustrative examples.